In the 3rd Generation Partnership Project (3GPP), a radio access method and a radio network for the cellular mobile communication (hereinafter referred to as “Long Term Evolution (LTE)”, “Evolved Universal Terrestrial Radio Access (EUTRA)”, or “Evolved Universal Terrestrial Radio Access Network (EUTRAN)”) have been studied. In LTE, a base station device is also referred to as an evolved NodeB (eNodeB), and a terminal device is also referred to as user equipment (UE). LTE is a cellular communication system in which multiple areas each covered by the base station device are deployed to form a cellular structure. A single base station device may manage multiple cells.
LTE supports a time division duplex (TDD). LTE that employs the TDD scheme is also referred to as TD-LTE or LTE TDD. In TDD, uplink signals and downlink signals are time division multiplexed. Furthermore, LTE supports a frequency division duplex (FDD).
LTE provides a Hybrid Automatic Repeat reQuest (HARQ) functionality at Medium Access Control (MAC) layers. The HARQ functionality in the downlink has an asynchronous adaptive HARQ characteristic, and the HARQ functionality in the uplink has a synchronous HARQ characteristic (Non Patent Literature 1). Introduction of the asynchronous HARQ in the uplink has been studied in the 3GPP (Non Patent Literature 2).